Budget projections to be revised: Morrison

Whether the budget is still headed to balance in 2019/20 won't be known until the mid-year review in December.

Treasurer Scott Morrison says the projection of a return to budget will be revised. (AAP)

Treasurer Scott Morrison says the projection of a return to budget balance within four years will be revised by the end of the year.

The current budget papers project a balanced budget in 2019/20 after a series of deficits.

Asked whether he stood by the projection, Mr Morrison told Sky News on Tuesday the latest figures would not be known until the mid-year economic and fiscal outlook due in December.

"Those projections and those forecasts will be revised in MYEFO and refreshed," Mr Morrison said.

Mr Morrison said it was crucial that when the budget books were balanced the government continued to keep spending less than revenue.